Fixed MSMF video capture (camera) issues

1. First patch fixes problems with finding suitable frame format when videoDevice::findType() is called with default parameters during video capture object initialization which causes reporting its state as closed after initialization (function isOpened() returns false).
cv::VideoCapture cap(CV_CAP_MSMF);
bool state = cap.isOpened();  // always false
2. Second patch fixes assertion warnings thrown when frames are being grabbed ('atlmfc\include\atlcomcli.h   Line:177   Expression: p==0'). These warnings occur because smart pointer is not reset at every loop (in ImageGrabber::startGrabbing).